Patterns of parasite abundance and distribution in island populations of Galápagos endemic birds

Parasite life-history characteristics, the environment, and host defenses determine variation in parasite population parameters across space and time. Parasite abundance and distribution have received little attention despite their pervasive effects on host populations and community dynamics. We used analyses of variance to estimate the variability of intensity, prevalence, and abundance of 4 species of lice (Insecta: Phthiraptera) infecting Galápagos doves and Galápagos hawks and 1 haemosporidian parasite (Haemosporida: Haemoproteidae) infecting the doves across island populations throughout their entire geographic ranges. Population parameters of parasites with direct life cycles varied less within than among parasite species, and intensity and abundance did not differ significantly across islands. Prevalence explained a proportion of the variance (34%), similar to infection intensity (33%) and parasite abundance (37%). We detected a strong parasite species-by-island interaction, suggesting that parasite population dynamics is independent among islands. Prevalence (up to 100%) and infection intensity (parasitemias up to 12.7%) of Haemoproteus sp. parasites varied little across island populations.     

Dispersal ability of island endemic plants: What can we learn using multiple dispersal traits?

Island endemic species are expected to have lower dispersal ability than their non-endemic congeners. Several studies have demonstrated differences in diaspore morphology between endemic species and their non-endemic congeners. It is, however, relatively difficult to translate the differences in morphology of the diaspores into differences in dispersal ability. To avoid this problem, we measured directly dispersal values (anemo-, hydro-, exozoo- and endozoo-chory) of 27 pairs of closely related endemic and non-endemic species from Canary Islands. We did not explicitly support the hypothesis about the loss of dispersal ability of island species. The comparison of pairs of endemic and non-endemic species showed the reduction in dispersal potential only for endozoochory. In many cases, endemic species had, in fact, the same or better dispersal ability than their non-endemic congeners. Higher dispersal ability of endemic species could have been evolved as a consequence of species subsequent dispersal to neighboring islands. As a support for this we found that the endemic species dispersing better than their non-endemic congeners also occupy more islands within the archipelago. We conclude that reduction of dispersal ability of species on islands may not be as general as previously expected and we need to take into account multiple species traits to understand the possible evolution of species dispersal potential.     

Conservation genetics of two island endemic Ribes spp. (Grossulariaceae) of Sardinia: survival or extinction?

Measuring levels of population genetic diversity is an important step for assessing the conservation status of rare or endangered plant species and implementing appropriate conservation strategies. Populations of Ribes multiflorum subsp. sandalioticum and R. sardoum, two endangered endemic species from Sardinia, representing the whole genus on the island, were investigated using ISSR and SSR markers to determine levels and structure of genetic variability in their natural populations. Results indicated medium to low genetic diversity at the population level: Nei's gene diversity for ISSR markers ranged from 0.0840 to 0.1316; the expected heterozygosity (H_E) for SSR ranged from 0.4281 to 0.7012. In addition, only one remnant population of R. sardoum showed a high level of inbreeding, in accordance with its very small size. Regarding the structure of the six R. sandalioticum populations, both principal coordinates analysis (PCoA) and STRUCTURE analysis of ISSR and SSR data highlighted low population structure, although two populations appeared to be clearly distinct from the others. The genetic pattern of the two taxa associated with their different ecological positions indicated resilience of R. sandalioticum populations in fresh and humid habitats and uncertain future resistance for the residual R. sardoum population in xeric calcareous stands. Hence, this study highlights the importance of an integrated conservation approach (genetic plus in situ and ex situ conservation studies/measures) for activating management programmes in these endemic and threatened taxa that can be considered as crop wild relatives of cultivated Ribes species.     

Molecular differentiation within and among island populations of the endemic plant Scalesia affinis (Asteraceae) from the Galápagos Islands

Molecular variance was estimated in seven populations of the endemic species Scalesia affinis within and among islands of the Galapagos. The analysis, based on 157 polymorphic AFLP markers, revealed a high differentiation among populations, of which most was partitioned among islands. In addition, the information content of AFLP markers was tested with sets of discriminant analyses based on different numbers of AFLP markers. This indicated that the markers were highly informative in discriminating the populations. Although one of four populations from the island Isabela was sampled from a volcano 100 km away from the remaining populations, this population resembled the others on Isabela. The partitioning of molecular variance (AFLP) resulted in two unities, one consisting of populations from Isabela and one of populations from Santa Cruz and Floreana. The differentiation in two chloroplast microsatellites was higher than for AFLP markers and equally partitioned among populations within islands as among islands. Thus, gene flow via fruits within islands is as limited as among islands. The lower differentiation within islands in the nuclear AFLP markers may thus indicate that gene flow within islands is mostly accounted for by pollen transfer. S. affinis is the only species in the genus that is not listed in 2000 IUCN Red List of Threatened Species. However, due to prominent grazing and land exploitation, some populations have recently been reduced markedly, which was reflected in lower diversity. As inbreeding depression is present in the species, the rapid bottlenecks are threats to the populations.     

Behavioral and physiological adjustments to new predators in an endemic island species, the Galápagos marine iguana

For the past 5 to 15 million years, marine iguanas (Amblyrhynchus cristatus), endemic to the Galápagos archipelago, experienced relaxed predation pressure and consequently show negligible anti-predator behavior. However, over the past few decades introduced feral cats and dogs started to prey on iguanas on some of the islands. We investigated experimentally whether behavioral and endocrine anti-predator responses changed in response to predator introduction. We hypothesized that flight initiation distances (FID) and corticosterone (CORT) concentrations should increase in affected populations to cope with the novel predators. Populations of marine iguanas reacted differentially to simulated predator approach depending on whether or not they were previously naturally exposed to introduced predators. FIDs were larger at sites with predation than at sites without predation. Furthermore, the occurrence of new predators was associated with increased stress-induced CORT levels in marine iguanas. In addition, age was a strong predictor of variation in FID and CORT levels. Juveniles, which are generally more threatened by predators compared to adults, showed larger FIDs and higher CORT baseline levels as well as higher stress-induced levels than adults. The results demonstrate that this naive island species shows behavioral and physiological plasticity associated with actual predation pressure, a trait that is presumably adaptive. However, the adjustments in FID are not sufficient to cope with the novel predators. We suggest that low behavioral plasticity in the face of introduced predators may drive many island species to extinction.     

Is the incidence of malaria decreasing in endemic area of Turkey?

Much international business and tourism travels occur, as well as the deployment of soldiers to other places. The aim of this study was both to determine incidence of malaria in the military hospital, Diyarbakir, southeast region of Turkey, and to point out the incidence of this disease. During the study period (1997-2004), 609 cases were found in a military hospital, which is in an endemic area for vivax malaria. This article review trends in current malaria status as well as possible factors for the decreasing prevalence throughout the study period.     

The Hitchhiker’s guide to island endemism: biodiversity and endemic perennial plant species in roadside and surrounding vegetation

Roadsides are habitats with very specific environmental conditions, often substantially differing from their natural surroundings. However, roads can have a positive effect on local vascular plant species richness. Endemic species on oceanic islands are considered to be less disturbance-adapted than native non-endemics and thus should be negatively affected by roads. Islands provide optimal conditions for testing this, as they possess a large share of clearly defined endemic species. This study focuses on a comparison of endemic plant species in roadside and surrounding communities and the interacting effects of elevation, vegetation type and trade wind-induced precipitation differences. We applied 96 circular plots with 50 m radius along two elevational gradients on the eastern (humid) and western (dry) slope of La Palma, Canary Islands, ranging from 100 to 2,400 m. Interestingly, we found roads to have a significant positive effect on endemic richness and the percentage of endemics as well as the same tendency for plant species richness after correcting for elevation and precipitation. Endemic species turnover was relatively high. The opening of cliffs during construction and, not to be overlooked, the protection from disturbances such as fire and omnipresent introduced herbivores (mainly rabbits or goats) probably leads to a positive effect of roads on endemics. In addition, many endemics might profit from species-specific dispersal capabilities well suited for roadside conditions. However, we do not argue for the use or even construction of roads for nature conservation but suggest protecting existing endemic populations because natural areas have a higher conservation value.     

Gene flow between an endangered endemic iguana, and its wide spread relative, on the island of Utila, Honduras: when is hybridization a threat?

The island endemic Ctenosaura bakeri was listed as critically endangered by the IUCN Redlist Assessment in 2004, 7 years after it was recognized as a distinct species. C. bakeri occupies a portion of Utila, a small continental island located off the northern coast of Honduras. Habitat destruction and over-harvesting are among the top threats facing this species. In addition, morphological evidence of hybridization was recently documented, raising the concern that gene flow from the common and widely distributed C. similis could threaten the genetic distinctiveness of C. bakeri. We show that hybridization occurs only at low levels and is not a current threat to C. bakeri. All ctenosaurs captured for this study were identified to species level without difficulty; none had intermediate or mosaic phenotypes. Sequence analysis of mitochondrial and nuclear markers revealed only two individuals with introgressed genotypes. Molecular analysis of the previously described hybrid showed it to be heterozygous for C. bakeri and C. similis alleles. Hybridization between these two species is possible and occurs occasionally in the wild, and the rate of hybridization could increase if habitat destruction or changes in relative abundance increase the probability of interbreeding. However, the level of gene flow indicated by current data is too low to threaten C. bakeri with genetic swamping or deleterious fitness effects.     

The contribution of island populations to in situ genetic conservation

Genetic variation is often lower within island populations, however islands may also harbor divergent genetic variation. The likelihood that insular populations are genetically diverse or divergent should be influenced by island size and isolation. We tested this assumption by comparing patterns of genetic variation across all major island song sparrow populations along the Pacific North American coast. Allelic richness was moderately lowered even on islands which are close to large, potential sources. The most significant differences in allelic richness occurred on very small or highly remote islands. Gene diversity was significantly lower only on remote or very small islands. We found that island populations contribute to regional genetic variation through both the amount of genetic variation and the uniqueness of that variation. The partitioning of this contribution was associated with the size and isolation of the island populations.     

Threatened species, a re-evaluation of the status of eight endemic plants of the Gala´pagos

Although still in relatively good condition, the Gala´pagos Archipelago suffers from increasing human pressures. Apart from direct actions like hunting and logging, endemic plants and animals are threatened by introduced species, and in many cases the present status of the populations is not known. The conservation status of eight plant species considered endangered was studied from literature and field surveys and the main threats were determined. Each of the eight species is endemic to only one island but in some cases is also present on nearby islets. Of these eight species, one is considered extinct, one critically endangered, and the others suffer various levels of threat. As in all island systems of the world, the main threats are introduced organisms, both plants and animals. The extinct species probably disappeared owing to invasion by Lantana camara, one of the most aggressively invasive plants of the islands, and the most endangered species is threatened by goats. The remaining species seem to be regenerating well and we can expect positive results from protection efforts. Today, only one of the eight species benefits from a direct protection action.     

The effects of land-use policies on the conservation of Borneo’s endemic Presbytis monkeys

Despite supporting the highest biodiversity on Earth, tropical rainforests are undergoing intensive economic development. In particular, the island of Borneo has lost over 56 % of original lowland forest to resource extraction, fires, and illegal logging. Its rainforests contain 16 primate species, which serve as excellent ‘umbrella’ taxa for conservation initiatives. The genus Presbytis (Colobinae) is well represented across Borneo by four endemic species (P. chrysomelas; P. frontata; P. hosei, and P. rubicunda), but remains relatively understudied. Using ecological niche modelling, I calculated the distributions of the 12 Bornean Presbytis subspecies; evaluated habitat loss between 2000 and 2010, and examined the current land-use policies across remnant distributions. Subspecies experienced a mean 12.7 % (N = 12 sp.) habitat reduction over the 10 year period. 12.5 % of all habitats were allocated for conversion to oil palm and industrial tree plantations, while logging concessions accounted for a mean 26.3 % across distributions. While the current protected area networks encompassed an average 33.4 % of distributions, most PAs are underfunded, degraded and threatened by logging and mining operations. I therefore recommend priority gazetting of unallocated lands to new PAs within the distribution of Presbytis chrysomelas and Presbytis hosei sabana, which have experienced the highest forest loss in the last 10 years (22–50 %) and are critically endangered. Logging concessions appear to be at least as effective in maintaining forest cover as PAs and have the economic advantage for effective management, but may have detrimental effects to monkey populations. I recommend an urgent assessment of the effects of selective logging practices on species’ persistence, and further recommend population surveys to quantify the populations of critically endangered and data deficient subspecies.     

Metacommunity,mainland‐island system or island communities? Assessing the regional dynamics of plant communities in a fragmented landscape

Understanding the regional dynamics of plant communities is crucial for predicting the response of plant diversity to habitat fragmentation. However, for fragmented landscapes the importance of regional processes, such as seed dispersal among isolated habitat patches, has been controversially debated. Due to the stochasticity and rarity of among‐patch dispersal and colonization events, we still lack a quantitative understanding of the consequences of these processes at the landscape‐scale. In this study, we used extensive field data from a fragmented, semi‐arid landscape in Israel to parameterize a multi‐species incidence‐function model. This model simulates species occupancy pattern based on patch areas and habitat configuration and explicitly considers the locations and the shapes of habitat patches for the derivation of patch connectivity. We implemented an approximate Bayesian computation approach for parameter inference and uncertainty assessment. We tested which of the three types of regional dynamics – the metacommunity, the mainland‐island, or the island communities type – best represents the community dynamics in the study area and applied the simulation model to estimate the extinction debt in the investigated landscape. We found that the regional dynamics in the patch‐matrix study landscape is best represented as a system of highly isolated ‘island’ communities with low rates of propagule exchange among habitat patches and consequently low colonization rates in local communities. Accordingly, the extinction rates in the local communities are the main drivers of community dynamics. Our findings indicate that the landscape carries a significant extinction debt and in model projections 33–60% of all species went extinct within 1000 yr. Our study demonstrates that the combination of dynamic simulation models with field data provides a promising approach for understanding regional community dynamics and for projecting community responses to habitat fragmentation. The approach bears the potential for efficient tests of conservation activities aimed at mitigating future losses of biodiversity.     

Is endemic stability of tick-borne disease in cattle a useful concept?

Endemic stability is a widely used term in the epidemiology of ticks and tick-borne diseases. It is generally accepted to refer to a state of a host-tick-pathogen interaction in which there is a high level of challenge of calves by infected ticks, absence of clinical disease in calves despite infection, and a high level of immunity in adult cattle with consequent low incidence of clinical disease. Although endemic stability is a valid epidemiological concept, the modelling studies that underpinned subsequent studies on the epidemiology of tick-borne diseases were specific to a single host-tick-pathogen system, and values derived from these models should not be applied in other regions or host-tick-pathogen systems.     

Multidisciplinary prospective study of mother-to-child chikungunya virus infections on the island of La Réunion

Background

An outbreak of chikungunya virus affected over one-third of the population of La Réunion Island between March 2005 and December 2006. In June 2005, we identified the first case of mother-to-child chikungunya virus transmission at the Groupe Hospitalier Sud-Réunion level-3 maternity department. The goal of this prospective study was to characterize the epidemiological, clinical, biological, and radiological features and outcomes of all the cases of vertically transmitted chikungunya infections recorded at our institution during this outbreak.

Methods and Findings

Over 22 mo, 7,504 women delivered 7,629 viable neonates; 678 (9.0%) of these parturient women were infected (positive RT-PCR or IgM serology) during antepartum, and 61 (0.8%) in pre- or intrapartum. With the exception of three early fetal deaths, vertical transmission was exclusively observed in near-term deliveries (median duration of gestation: 38 wk, range 35–40 wk) in the context of intrapartum viremia (19 cases of vertical transmission out of 39 women with intrapartum viremia, prevalence rate 0.25%, vertical transmission rate 48.7%). Cesarean section had no protective effect on transmission. All infected neonates were asymptomatic at birth, and median onset of neonatal disease was 4 d (range 3–7 d). Pain, prostration, and fever were present in 100% of cases and thrombocytopenia in 89%. Severe illness was observed in ten cases (52.6%) and mainly consisted of encephalopathy (n = 9; 90%). These nine children had pathologic MRI findings (brain swelling, n = 9; cerebral hemorrhages, n = 2), and four evolved towards persistent disabilities.

Conclusions

Mother-to-child chikungunya virus transmission is frequent in the context of intrapartum maternal viremia, and often leads to severe neonatal infection. Chikungunya represents a substantial risk for neonates born to viremic parturients that should be taken into account by clinicians and public health authorities in the event of a chikungunya outbreak.     

Characterization of canarypox-like viruses infecting endemic birds in the Galápagos Islands

The presence of avian pox in endemic birds in the Galápagos Islands has led to concern that the health of these birds may be threatened by avipoxvirus introduction by domestic birds. We describe here a simple polymerase chain reaction-based method for identification and discrimination of avipoxvirus strains similar to the fowlpox or canarypox viruses. This method, in conjunction with DNA sequencing of two polymerase chain reaction-amplified loci totaling about 800 bp, was used to identify two avipoxvirus strains, Gal1 and Gal2, in pox lesions from yellow warblers (Dendroica petechia), finches (Geospiza spp.), and Galápagos mockingbirds (Nesomimus parvulus) from the inhabited islands of Santa Cruz and Isabela. Both strains were found in all three passerine taxa, and sequences from both strains were less than 5% different from each other and from canarypox virus. In contrast, chickens in Galápagos were infected with a virus that appears to be identical in sequence to the characterized fowlpox virus and about 30% different from the canarypox/Galápagos group viruses in the regions sequenced. These results indicate the presence of canarypox-like viruses in endemic passerine birds that are distinct from the fowlpox virus infecting chickens on Galápagos. Alignment of the sequence of a 5.9-kb region of the genome revealed that sequence identities among Gal1, Gal2, and canarypox viruses were clustered in discrete regions. This indicates that recombination between poxvirus strains in combination with mutation led to the canarypox-like viruses that are now prevalent in the Galápagos.     

Effects of bird ingestion on seed germination of four woody species of the temperate rainforest of Chiloé island, Chile

We study the effect of ingestion by birds on seed germination and theconsequences of absence of dispersal, with the persistency of the seedsinside the fruit. We collected seeds of four woody species ofthe temperate rainforest of Chiloé: Gaultheriamucronata, Luma apiculata, Myrteolanummularia, and Myrceugenia planipes. The seedstested had the following origins: 1) Ingested seeds: seeds collected fromthe feces of birds, 2) Extracted seeds: seeds obtained directly from thefruits, and 3) Intact fruits: fruits collected directly from the plants.Germination of Myrceugenia planipes under greenhouseconditions, Luma apiculata, and Myrteolanummularia under laboratory conditions, and Gaultheriamucronata under both conditions was analyzed. We found that the seedsreach their maximum germination between 15–20 days after sowing, withthe exception of those of G. mucronata sown in the greenhouse,which showed a low germination rate. In the greenhouse assay, seeds ofG. mucronata ingested by birds, seeds extracted manuallyfrom the fruits, and seeds inside the fruits did not show significant differencesin their germination percentages. In the laboratory assays, the seeds ofG. mucronata and M. nummulariaingested by birds and the seeds extracted manually from the fruits also did not show anysignificant difference in germination. Under laboratory conditions, theseeds of L. apiculata ingested by birds presented astatistically greater percentage of germination than the seeds extracted manually.Under greenhouse conditions, seeds of M. planipes ingestedby birds did not present a statistically different germination percentage fromthose seeds extracted from the fruits. The seeds of M.planipes, and L. apiculata inside the intactfruits did not germinate. We conclude that birds do not affect the seedviability of any of the four species studied.     

Double invasion of Tertiary island South America by ancestral New World monkeys?

Comparative Determinant Analysis was used to characterize antigenic determinants from 69 functionally diverse serum proteins for the phylogenetic study of anthropoid cladogenesis, of which 32 homologues with 66 antigenic determinants were compared between Lagothrix lagotricha and Cebus albifrons. Nine epitopes (one each of complement factors Cls, C3, C6, C7, C9, factor B, retinol-binding protein, β₂-glycoprotein III, and histidine rich α₂-glycoprotein) defined a robust clade uniting Lagothrix lagotricha with the Old World primates Macaca, Papio and Homo to the exclusion of Cebus albifrons. This tree indicates platyrrhine paraphyly or demonstrates an accelerated antigen substitution rate of Cebus when compared with Lagothrix. Narrow phylogenetic sampling does not permit the final resolution of this problem but strongly different evolutionary rates are considered unlikely because ancestral serum protein determinants, which are plesiomorphic for Primates as an order, are equally conserved in both Cebus and Lagothrix. If platyrrhine paraphyly is correct, our molecular-immunological clock estimates a divergence date of Cebus of 52.5 × 10⁶ years before present, i.e. 6.5 × 10⁶ years before the ateline clade diverged (possibly at 46.0 × 10⁶ years BP) from catarrhine ancestors. A scenario of platyrrhine paraphyly implies the necessity for double invasion of the isolated Tertiary South American island continent by primates across open ocean, and suggests a considerably earlier phylogenetic emergence of platyrrhines than is proposed by the oldest simian fossils from the Neotropics.     

Genetic structure of fragmented populations of a threatened endemic percid of the Rhône river: Zingel asper

Zingel asper is an endemic percid of the Rh?ne basin considered to be critically endangered. This species was continuously distributed throughout the Rh?ne in 1900, but today only occupies 17% of its initial area. In the present study, five microsatellite loci were used to assess the level of genetic variability within and among populations localized in different sub-basins. Contrasting results were obtained for the three main populations from the Rh?ne. A reduced allelic diversity was observed for the two populations displaying the lowest patch sizes (length of the river system occupied); of these, a recent genetic bottleneck was detected for the population showing a particularly low density. However, the third population was characterized by a relatively large spatial extent, high local fish concentrations and an allelic diversity that was twice as high and associated with an equilibrium between mutation and drift. Thus, this population shows an apparently better evolutionary potential for long-term survival. Since 1930, a marked fragmentation of the whole Rh?ne system has appeared, related to the development of dams, and we assume that the significant genetic differentiation detected between the populations could mainly reflect the impact of this fragmentation. The high turnover of the Z. asper populations, and the major role of dispersal in population persistence (highlighted in a recent population dynamics study), indeed suggest that the differentiation observed could mainly have arisen from habitat fragmentation in recent history.